Generally, the shaft (metal rod) of an umbrella has a structure wherein a ferrule is disposed on the top end and a handle is disposed on the bottom end, an upper runner on which the ends of the multiple ribs pivot is fixed to the upper part, and a lower runner on which the ends of the stretchers attached to the middle of each of the ribs pivot is affixed to the bottom part such that it slides freely.
FIG. 22 is a perspective view of an example of a lower runner of the prior art, where a cylindrically-shaped lower runner 2 attached to a shaft 1 such that it can slide freely is coaxially integrated with a flange portion 3 on the top of a boss portion 23, this flange portion 3 has grooves 5 which hold the ends of each of stretchers 4 and are located radially around the rim on the top surface of the flange portion 3, and a groove 6 for holding the wire is formed on the outer surface of the flange portion 3 such that it intersects with the stretcher holder grooves 5.
Also, when linking the stretchers 4 to the lower runner 2, a wire (finishing wire) 7 is passed sequentially through axial holes 4a provided on the ends of the stretchers 4, and as the ends are inserted in the stretcher holder grooves 5, the wire 7 is laid in groove 6 and the ends of the wire 7 are twisted together, whereby the wire 7 takes on a ring shape and supports the ends of the stretchers 4 so that they can pivot. A twisted member 7a of the wire 7 is generally pressed into a groove 9 on the outer surface of a protrusion 8 protruding from the top surface of the flange portion 3.
Similarly, wire is passed sequentially through the axial holes on the ends of the ribs and the ends of the wire are twisted together and support the ends of the ribs such that they can pivot on the upper runner.
However, in this kind of umbrella runner, it is necessary to the pass wire 7 through the axial holes 4a at the ends of the stretcher and twist the wire together in order to support the ends of the stretchers such that they can pivot, and this operation is difficult and is extremely difficult to automate. Another problem occurs when the umbrella is repeatedly opened and closed, which causes the twisted member 7a of the wire 7 to become loose, thus allowing the stretchers to rattle or causing other problems.
Further, not only does the presence of the wire 7 which links the ends of the stretchers detract from the appearance, the end of the twisted member 7a which can become loose due to repeated opening and closing of the umbrella may injure a finger or catch on clothing and damage it.
To prevent that, covering of said twisted member 7a by heat-shrink synthetic resin tubing (Japanese Utility Model Registration No. 3017521) or covering the end of the twisted member 7a with melted synthetic resin (Japanese Utility Model Registration No. 3023762) have been proposed, but this kind of processing in addition to twisting the ends of the wire 7 together makes the operation of linking the umbrella stretchers even more difficult.
Also, in order to improve the umbrella stretcher linking operation, various stretcher pivoting structures that eliminate the wire passed through the axial holes in the ends of the stretchers have been proposed; for example, in Japanese Utility Model Publication No. 3(1991)-7714, a runner structure is proposed wherein bulb members are formed on the ends of the stretchers while bulb-shaped holes corresponding to said bulb members are provided in the runner, and the bulb members of the stretchers are press-fitted into these holes, thus providing pivot support of the ends of the stretchers.
However, in this kind of stretcher pivoting structure, a special stretcher in which bulb members are formed on the ends, for example, is required thus making it impossible to use conventional stretchers with the axial holes 4a in the ends.
In view of the above situation, the purpose of this invention is to greatly simplify the operation of linking the stretchers to the runner and also make automation possible while allowing the use of conventional stretchers by eliminating the wire passed through the axial holes in the ends of the stretchers.